I've included a sample picture and the location of the components in the picture below It's highly unlikely that it's your logic board or a component of your logic board, but the possibilities are: There are only a few components in an iMac that can make clicking noises.

It also makes this sound when the display is off, so it could be like said that it is the power supply. I feel if I take the iMac in and describe the issue they will send the iMac away for few weeks and it will be sent back saying there isn't any issues. I tried to blow some air in the GPU vents which didn't change anything. I ran the hardware diagnostic test (Holding D when you restart) which resulted in no errors. I doesn't sound like a bad fan as it's a very clicky noise versus a whine or hum. Also changing the brightness causes the noise.Running a web GPU benchmark or watching a video will make the noise constant until I close it.The noises increase when scrolling a webpage or change workspaces and then subside when I stop.Last night my iMac started making noises similar to that of a disk drive when it's reading and writing.Īfter poking around I found that the noise must be related to the GPU because: I have a late 2014 5k iMac with 256GB SSD drive.